Butter a round baking pan (diameter of about 24 to 26 cm) and lay the placinta dough. Boil about 900 ml of milk with 100 g of sugar. Beat the eggs with remaining sugar, add sifted flour, then remaining milk (100 ml). Add hot milk little by little, then put everything on fire, stirring until creamy.Turn off the heat, let it cool a bit, after that add sour cream and vanilla (you can put some chocolate too). Pour the mixture into the pan and cook it in the baking oven for at least one hour at a right temperature. Let it cool, after that put it in the refrigerator.